NCV7381 Просмотр технического описания (PDF) - ON Semiconductor
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NCV7381 Datasheet PDF : 24 Pages
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NCV7381
Bus Guardian Interface
The interface consists of the BGE digital input signal
allowing a Bus Guardian unit to disable the transmitter and
of the RxEN digital output signal used to signal whether the
communication signal is Idle or not.
Bus Driver Voltage Regulator Control
NCV7381 provides a high−voltage output pin INH which
can be used to control an external voltage regulator (see
Figure 2). The pin INH is driven by a switch to VBAT supply.
In Normal, Receive−only, Standby and Go−to−Sleep modes,
the switch is activated thus forcing a High level on pin INH.
In the Sleep mode, the switch is open and INH pin remains
floating. If a regulator is directly controlled by INH, it is
then active in all operating modes with the exception of the
Sleep mode.
uBus
Bus Driver Remote Wakeup Detection
During a low−power mode and under the presence of
VBAT voltage, a low−power receiver constantly monitors the
activity on bus pins BP and BM. A valid remote wake−up is
detected when either a wakeup pattern or a dedicated
wakeup frame is received. A valid remote wake−up is also
detected when wake−up pattern has been started in
normal−power mode already.
A wakeup pattern is composed of two Data_0 symbols
separated by Data_1 or Idle symbols. The basic wakeup
pattern composed of Data_0 and Idle symbols is shown in
Figure 6; the wakeup pattern composed of Data_0 and
Data_1 symbols – referred to as “alternative wakeup
pattern” − is depicted in Figure 7.
<dWUTimeout
>dWU0Detect
>dWUIdleDetect
>dWU0Detect
>dWUIdleDetect
0
uData0_LP
Idle(_LP)
Data_0
Idle(_LP)
Data_0
Figure 6. Valid Remote Wakeup Pattern
Idle(_LP)
uBus
>dWU0Detect
<dWUTimeout
>dWUIdleDetect
>dWU0Detect
>dWUIdleDetect
0
uData0_LP
Idle(_LP)
Data_0
Data_1
Data_0
Data_1
Figure 7. Valid Alternative Remote Wakeup Pattern
A remote wakeup will be also detected if NCV7381 receives a full FlexRay frame at 10 Mbit/s with the following payload data:
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0x00,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
The wakeup pattern, the alternative wakeup pattern and the wakeup frame lead to identical wakeup treatment and signaling.
Local Wakeup Detection
The high−voltage input WAKE is monitored in
low−power modes and under the condition of sufficient
VBAT supply level. If a falling edge is recognized on WAKE
pin, a local wakeup is detected. In order to avoid false
wakeups, the Low level after the falling edge must be longer
than dWakePulseFilter in order for the wakeup to be valid.
The WAKE pin can be used, for example, for switch or
contact monitoring.
Internal pull−up and pull−down current sources are
connected to WAKE pin in order to minimize the risk of
parasitic toggling. The current source polarity is
automatically selected based on the WAKE input signal
polarity – when the voltage on WAKE stays stable High
(Low) for longer than dWakePulseFilter, the internal current
source is switched to pull−up (pull−down).
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